extern uschar *spool_dname(const uschar *, uschar *);
extern uschar *spool_fname(const uschar *, const uschar *, const uschar *, const uschar *);
extern uschar *spool_dname(const uschar *, uschar *);
extern uschar *spool_fname(const uschar *, const uschar *, const uschar *, const uschar *);